ITU-T recommends an OTN (Optical Transport Network) where packet data may be integrally handled as a next-generation optical transportation technique expected to be used in more application fields.
In the OTN, it is possible to integratively handle TDM-based data such as SONET (Synchronous Optical Network)/SDH (Synchronous Digital Hierarchy) and packet-based data in the Ethernet (registered trademark, and hereinafter may be simplified as a “LAN” (Local Area Network))
The OTN includes specifications of ODUflex (Optical Channel Data Unit flex) providing a variable bandwidth in response to a demand to effectively transmit packet-based data which are currently main traffic data.
As described, in the data transmission based on the OTN, by providing the variable bandwidth in response to a demand, it becomes possible to effectively transmit the packet-based data.
Specifically, there is a known technique where to effectively transmit the packet-based data, the correspondence between a tributary slot in a frame signal and a client signal is managed, and based on the correspondence, a demapping process from the frame signal to the client signal is performed. Reference may be made to Japanese Laid-open Patent Publication No. 2011-55199.